This disclosure relates generally to photoreceptor that facilitates removal of the photoreceptor coatings disposed over an electrophotographic photoreceptor and environmentally or “green” methods for using the same. More specifically, the present embodiments disclose a photoreceptor that includes a specifically formulated undercoat layer that allows easy removal of the photoreceptor layers disposed on top of the undercoat layer. The present embodiments provide a simple yet efficient method for reclaiming recycling or remanufacturing electrophotographic photoreceptors.
In electrophotography, the substrate for photoreceptors in a rigid drum format is required to be manufactured with high dimensional accuracy in terms of straightness and roundness, optimum surface reflectance and roughness, and desired thickness. In order to obtain such a dimensional accuracy, the substrate surface is polished at a high accuracy by using sand blustering, glass bead honing, or a diamond tool and/or the like. Once the substrate surface is formed, at least one coating of photosensitive material is applied to the substrate, which may comprise a charge generation layer and a charge transport layer, or their blended in a single layer, to form a full photoreceptor device.
Current photoreceptor may be commonly comprised of an aluminum substrate having specific dimensions required for straightness, roundness and counter bore concentricity. For example, the wall needs to be minimized for efficient raw material cost but also thick enough to meet the one time machining requirements and physical requirements of the finished photoreceptor device. A defect-free surface with maximum reflectivity is provided by diamond machining to a mirror finish followed by glass bead honing. A maximum surface roughness is also specified. Preparation of the aluminum substrate surface is important in maintaining uniform, defect-free print quality. Minimizing the reflectivity of the surface, eliminates a defect causes by surface reflections that has the appearance of a plywood patterns in half tone areas of prints. Exceeding the maximum surface roughness leads to charge injection and high background.
The final product generally comprises three organic coatings, an undercoat layer (UCL), that functions as a primer, a charge generation and a charge transport, and in some cases, an anti-reflective coating and hole blocking layer. The final assembly has two end caps (or flanges). One end cap comprises a drive gear and the other end cap comprises of a bearing and ground strap that has a spring contact to the bearing shaft and a friction contact to the inner substrate surface. The end caps are held in place with an epoxy adhesive and must meet a specified torque and push out force after a specified thermal cycle test condition.
The fabricated photoreceptor devices are expected to have good electrical and mechanical performance in a copier or printer. But, due to complexity of the manufacturing process, it is unavoidable to have varieties of defects in some photoreceptor devices which may not meet the quality requirements for the copier or printer. The defective devices have to be rejected. In another aspect, each photoreceptive device has limited application life. Once the photoreceptor device cannot function well in the machine, it is also the end of the application life of the device. These used photoreceptor devices were usually disposed in the same way as the defective devices were treated. Disposal of the device could be very costly and could cause lots of environmental issues.
Remanufacturing such a photoreceptor device is difficult because the device dimensions are very specific and minor changes can adversely impact the results. For example, there is a specific balance between the substrate surface reflectance and surface roughness that must be maintained. Moreover, such photoreceptors have wall thicknesses that are too thin to re-machine, the coating layers comprise polymers that are chemically resistant to all but the most aggressive, and often non-environmentally friendly, solvents. For example, organic photoreceptors with the current undercoat layers are very difficult to reclaim using the current acid/alcohol stripping solution at elevated temperatures.
Moreover, methods to effectively and completely remove coated photoreceptor layers from substrates for re-use are plagued by the necessity to use harsh chemicals including acids or solvents that frequently require large quantities that increase the costs for hazardous waste disposal and may pose safety concerns. A release layer to facilitate the removal of coated layers in an environmentally friendly solvent will reduce the cost of the substrate reclaiming process and result in significant cost savings by enabling substrate re-use.
Thus, there exists a need for safe and environmentally-friendly methods to recycle or reclaim electrophotographic photoreceptor devices that would address the above-identified problems. Furthermore, there is a need to reduce the cost of remanufacturing electrophotographic photoreceptors, for example, by recycling the non-usable photoreceptor devices, through removing the photosensitive or coating layers without damaging the substrate formation. This would not only reduce the cost of producing the photoreceptor, but also decreases the cost for disposing all related materials in the devices.
Conventional photoreceptors and their materials are disclosed in Katayama et al., U.S. Pat. No. 5,489,496; Yashiki, U.S. Pat. No. 4,579,801; Yashiki, U.S. Pat. No. 4,518,669; Seki et al., U.S. Pat. No. 4,775,605; Kawahara, U.S. Pat. No. 5,656,407; Markovics et al., U.S. Pat. No. 5,641,599; Monbaliu et al., U.S. Pat. No. 5,344,734; Terrell et al., U.S. Pat. No. 5,721,080; and Yoshihara, U.S. Pat. No. 5,017,449, which are herein all incorporated by reference.
More recent photoreceptors are disclosed in Fuller et al., U.S. Pat. No. 6,200,716; Maty et al., U.S. Pat. No. 6,180,309; and Dinh et al., U.S. Pat. No. 6,207,334, which are all herein incorporated by reference.
The terms used to describe the imaging members, their layers and respective compositions, may each be used interchangeably with alternative phrases known to those of skill in the art. For example, the term “photoreceptor” or “photoconductor” is generally used interchangeably with the terms “imaging member.” The term “electrophotographic” includes “electrophotographic” and “xerographic.” The terms “charge transport molecule” are generally used interchangeably with the terms “hole transport molecule.” The terms used herein are intended to cover all such alternative phrases.